This invention relates to propulsion units for boats and the like and in particular, to a new and improved water jet propulsion unit.
Water jets are widely used today for propulsion of watercraft, with the water jet being produced by an engine driven impeller in a housing rather than by a screw.
Water jet propulsion units are currently being produced by a large number of manufacturers, and a typical installation is shown in FIG. 1. The water jet propulsion unit 11 is mounted on the hull 12 of a boat, at the transom 13. Typically the water jet propulsion unit has a housing formed of a suction piece 14, a bowl 15, and a nozzle 16, with a reverse housing 17 and a reverse bucket 18 positioned at the outlet end of the nozzle. A planing plate 19 projects aft from the suction piece 14. An engine 20 is connected at the forward end of the suction piece of the housing by a mounting unit 21.
In operation, the engine drives an impeller in the bowl portion of the housing, with water being drawn in at an inlet 22 of the suction piece and driven outward through the nozzle 16 to provide the force which moves the vessel forward.
A typical water jet propulsion unit is shown in greater detail in FIG. 2, with a drive shaft 24 mounted in a thrust bearing 25 at the forward end of the housing and in another bearing 26 in a sleeve 27 of the bowl 15. The engine is connected at the forward end of the drive shaft and the impeller is carried at the aft end of the drive shaft. In this construction, the thrust bearing 25 is inserted into the housing from the forward end, resting against a shoulder 28 of the housing and being held in place by a bearing cap 29.
In the water jet propulsion units, it is often necessary to remove and service or replace the thrust bearing 25. With the present day construction as shown in FIG. 2, the thrust bearing must be moved forward relative to the housing. This requires either a forward movement of the engine or a rearward movement of the entire propulsion unit in order to remove the bearing cap and the thrust bearing. Both of these procedures are undesirable and time consuming.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a new and improved water jet propulsion unit in which the thrust bearing can be removed and replaced without requiring movement of the engine or movement of the portion of the propulsion unit connected to the boat.
It is a particular object of the invention to provide such a propulsion unit wherein the thrust bearing is inserted into the propulsion unit housing from the aft or rear end rather that from the forward end, and one wherein the drive shaft and thrust bearing can be removed from the fixed portion of the propulsion unit housing by merely removing the bowl and nozzle portion.
It is an additional object of the invention to provide such a unit utilizing a shaft seal unit for positioning around the shaft and within the housing, with the shaft, impeller, shaft seal unit and thrust bearing being insertable and removable as a unit from the rear end of the housing. A further object of the invention is to provide such a construction wherein the shaft seal unit can be fixed in position with a retainer insertable into the housing from a lateral opening.
It is a further object of the invention to provide such a unit in which a seal between the engine and the propulsion unit can be removed and replaced without movement of the engine or the portion of the propulsion unit connected to the boat.
These and other objects, advantages, features and results will more fully appear in the course of the following description.
The presently preferred embodiment of the water jet propulsion unit has a housing, a drive shaft, an impeller for mounting on the drive shaft, and a thrust bearing for supporting the drive shaft in the housing, and includes a shaft seal unit for the shaft, with the housing having a forward end and a rear end, a bore with a longitudinal axis for slidingly receiving the shaft seal unit from the rear of the housing, with the shaft seal unit and bearing carried on the shaft, a shoulder for preventing forward movement of the bearing in the bore along the axis beyond a predetermined position, and a lateral opening for access through the housing to the shaft seal unit, and a retainer moveable through the lateral opening for engagement with the shaft seal unit and the housing for limiting rearward movement of the shaft seal unit in the bore.